bug#13041: 24.2; diacritic-fold-search

[Juri Linkov]

> Emacs contains ucs-normailze package which provides various
> normalization functions.  For instance,
>
> (require 'ucs-normalize)
> (ucs-normalize-NFKD-string "Äffin") => "Äffin"
>
> Isn't it usable?

This is usable to sort and compare strings, but I don't see
how ucs-normalize.el could help in the search.  I suppose the
searched buffer can't be normalized before starting a search.
So the search function somehow should be able to skip combining
characters in the buffer.  But to do this, the translation table needs
to contain additional information about certain characters to ignore.
Also the translation table should be able to map a sequence of
characters like "ss" to "ß".